SOLUTIONS: Solar & Efficiency Pair Up for the Navajo Nation

Solar strategies, such as a tracked PV system and solar air heating (not pictured), pair up with a well-sealed and -insulated building envelope to create an energy-efficient off-grid house.

Beginner

“Nowhere in America are there more people without electricity than on tribal lands,” says Elsa Johnson of IINA Solutions. It’s estimated that nearly 20,000 rural Navajo homes do not have electricity—and are lacking typical household services many of us take for granted. The Plateau Solar Project (PSP)—a pilot project of IINA Solutions, Mark Snyder Electric, and Global Solar Water Power Systems (GSWPS)—is changing that by providing solar-electric systems, water, sanitation, and meaningful employment.

Like thousands of other rural Navajo families, the George family lived for years without running water or electricity in their home near Canyon Diablo, Arizona. The family of five shared a small, two-bedroom dwelling built with railroad ties, their only lighting from a single kerosene lantern. Twice a week, the Georges made a 50- to 70-mile journey through desert canyons on washboard dirt roads to get firewood and water. They’d never owned a refrigerator—or even a lightbulb—and only had an outhouse for bathroom facilities. Today, thanks to the PSP, the George family lives with electricity and running water in a modest, energy-efficient off-grid home powered by the sun and wind.

The new, 1,400-square-foot home’s construction was funded through a Bureau of Indian Affairs and Navajo Rural Housing Development special project. The home is fairly conventional—with 2-by-6 construction and fiberglass insulation in the walls (R-19) and attic (R-30). But infiltration in framing often reduces performance. To remedy this, 1/2-inch-thick P2000 rigid-foam insulation provides a whole-house thermal break, adds R-2.2 to the insulation, and reduces infiltration significantly. While the house isn’t oriented for passive solar gain (Navajo tradition dictates that a home’s front door face east), overhangs are designed to reduce summer heat gain through the windows.

The remote site, located on rugged Navajo land near Flagstaff, Arizona, and 15 miles from the nearest utility line, posed design challenges for meeting the home’s energy needs, thus the focus on energy efficiency first. Next was implementation of renewable energy systems—a small wind-electric turbine and 1.2 kW off-grid PV system provide electricity for the home’s few loads (LED and compact fluorescent lighting, an Energy Star refrigerator, and a few other small electronics).

Three SolarRoofs Skyline 10-05 solar air collectors coupled to a ducted recirculating system with a blower fan provide the main space heating. This is supplemented by a wood heater and 750-watt infrared heater mounted on an interior 13-by-8-foot brick (thermal) wall. Water is heated by a 750-watt diversion load from the wind-electric system (and from the PV system, when the batteries are on a float charge). Cooking is done on a propane stove, with the wood heater serving as the backup. In the summer, a GSWPS Silent Aire combination evaporative cooler and ventilator cools the house, using nighttime air from the outside.

Unique to the house is an Enertopia Multi-Purpose Utility Structure (EMPUS) Bump—an insulated 4-by-8-foot room attached to the house. The EMPUS serves as the home’s central energy station, containing the inverters and batteries for the wind and PV systems. The unit is insulated to R-30 and climate-controlled via its own solar hot air collector, which serves a heating and cooling function, depending on the season. A 500-gallon water tank absorbs heat from the Solar Aire heater/cooler. The combination of solar heating/cooling and insulation helps the EMPUS maintain temperatures between 45°F and 85°F, despite chilling winter lows and sweltering summer highs.

Once the unit reaches 85°F, it transfers up to 750 Btu of excess heat into the house via a blower fan. A thermostatically controlled infrared wall-mounted heater in the living room uses surplus electricity from the RE systems to heat the thermal wall for up to three hours—even after the fire has gone out in the wood heater. A ventilation system built into the EMPUS unit controls the humidity in the house and ensures adequate air exchanges between the interior and exterior.

Sensors throughout the house monitor and log data on temperature, humidity, and power consumption. This data is shared with several agencies to track the home’s performance. The George family pays a $35 monthly fee to MSE to cover servicing, maintenance, and component replacement in the RE systems.

Off-Grid Hybrid System

Five 240 W Day4Energy 60MC-I PV modules are mounted on a Zomeworks passive tracker. Along with adjusting the array tilt four times a year, at the equinoxes and solstices, the tracker has an “early wake-up” system (patent pending by Mark Snyder), which faces the tracker east before sunrise and helps optimize the system’s production.

A 1 kW Navajo Niyol wind generator from Cherokee WindPower takes advantage of cyclonic winds that sweep the plateau at night, contributing some electricity to the hybrid system’s mix.

So far, the PSP has brought renewable electricity to more than 40 Navajo elders. They’ve trained eight Navajo workers to plumb, rewire, and retrofit houses, and to maintain existing RE systems. But, says Mark, this is just the first step. MSE and IINA Solutions are looking for additional partners to help them bring power—and hope—to underprivileged tribal communities here and across the world.